Such lock devices are required e.g. for vacuum-supported coating processes, e.g. to increase gas-tightness of PET bottles which to this end are usually treated in a vacuum of about 10 to 40 mbar. For this, continuous locking in and out is indispensible for an economical manufacturing process.
A generic lock device is known e.g. from EP 0943699 B1. This lock comprises a revolving housing with a lock chamber wheel rotatably mounted therein in which lock chambers with openings for loading and unloading containers to be locked are provided on the circumference.
The revolving housing comprises suction pipes for evacuating the lock chambers which are atmospherically sealed from each other by circumferential seals on the lock wheel. The lock chambers between the charging and the discharging station, respectively, in the outer room and the evacuated treatment room form a differential pressure stage, the lock chamber pressure being reduced revolving in the direction of the treatment room, from the atmospheric pressure usually prevailing in the outer room to the pressure prevailing in the treatment room.
However, due to the complicated manufacture of the revolving housing and the lock chamber wheel, a subsequent adaptation of the device to different container sizes and shapes is expensive or not possible at all. To be able to also for large containers provide sufficiently large lock chambers in a number sufficient for the differential pressure stage, it is moreover necessary to correspondingly increase the diameter of the lock wheel. This involves a wide structural shape which might be undesired.
Another lock device known from DE 27 47 061 A is used to lock tapes into or out of a vacuum coating chamber through a pressure stage section. The lock device comprises several fixed lock chambers arranged one behind the other and separated from each other with slit-like diaphragms. The tape to be coated is transported through the slit diaphragms and the lock chambers on a backing tape. To be able to generate a drop of pressure between the chambers, the diaphragms must be adapted to the cross-section of the backing tape and the tape to be coated. Such a device, however, is not practicable for locking in and out containers, as these, in contrast to a tape, do not comprise a constant cross-section seen in the moving direction, or as gaps between the individual bottles are inevitable.